**5. PEF treatment effects on the physicochemical and sensory properties of wine**

One of the main concerns regarding the use of preservation techniques in the wine industry lies in their potentially negative effects on the quality characteristics of wines. As a non-thermal technology, Pulsed Electric Fields presents the advantage of having great effectivity in terms of microbial decontamination with minimum alteration of the physicochemical and nutritional properties of foods [45]. A series of studies have reported that PEF has no significant effects on the main physicochemical and sensorial quality parameters of must and wine, immediately after treatment or after a period of storage [24]. What is more, some of these studies have reported better sensory attributes for PEF-decontaminated wines in comparison with untreated wines or wines treated with SO2.

#### *Microbial Decontamination by Pulsed Electric Fields (PEF) in Winemaking DOI: http://dx.doi.org/10.5772/intechopen.101112*

After six months of storage, the physicochemical composition of three PEFtreated wines showed no differences in pH, total acidity, anthocyanin content, or total polyphenol index, but they displayed better quality in terms of volatile acidity and color intensity [41]. Moreover, sensorial analysis indicated that the organoleptic properties of the wines treated with PEF combined with SO2 (15 mg/L) had the highest scoring values in comparison with wines treated only with PEF or treated only with SO2 (30 mg/L). In white wines, intense PEF treatments of 20 kV/cm and 6 ms had an effect similar to the addition of sulfur dioxide (250 mg/L), but with a notable decrease of the browning effect [35].

Moreover, the application of PEF treatments combined with mild temperatures has been proven to significantly increase microbial inactivation levels [22, 23]. In this context, Abca & Evrendilek studied changes in the attributes of wine treated by PEF combined with different temperatures for purposes of microbial inactivation [34]. For all the strains studied (*E. coli, L. bulgaricus, C. lipolytica, S. cerevisiae*, *and H. anomala*), an increment of the treatment temperature from 10 to 30°C improved the lethal effect by at least 1.5 log cycles. Even the most intense treatment (31 kV/ cm, 30°C) did not show any significant changes in pH level, °Brix, titratable acidity, color, anthocyanin, antioxidant capacity, total polyphenolic content, and sensorial properties.

Until now, no study has shown any significant negative effects on the sensory properties of wine treated by PEF. Further research should nevertheless be carried out with optimized PEF-parameters for microbial stabilization in the different steps of winemaking, and featuring different grape/wine varieties.

Among potentially negative effects of PEF, another important concern is the possible migration of ion metals from the electrodes to the food matrix. Although certain authors have reported the release of ion metals, this phenomenon seems to be thoroughly dependent on electrode material and geometry, as well as on processing parameters (conductivity, electric field strength, total specific energy, pulse width) [46, 47]. In wine, the increase of certain metal ions (e.g. arsenic, calcium, mercury, iron, copper, magnesium, and selenium, among others) can cause turbidity and a metallic taste; it can even represent a health risk for consumers. In red wine, Abca & Evrendilek did not observe significant differences in the concentration of 13 different metal ions between PEF and control wines, even at highest-intensity PEF conditions (31 kV/cm, 30°C) [34]. Similarly, no differences in iron and chromium concentration were detected in Cabernet Sauvignon red wine subjected to 34 and 53 kV/cm (50us) treatments [39]. Although those treatments slightly increased the concentration of nickel in the PEF-treated wines the levels reached were below the maximum limits permitted in food products.
